Vapor compression system

ABSTRACT

An evaporator for use in a vapor compression system is disclosed. The evaporator may include an enclosure that covers a substantial portion of a tube bundle in the evaporator. The enclosure substantially prevents refrigerant vapor, generated as a result of the heat transfer with the tube bundle, from flowing laterally between tubes of the tube bundle. Various configurations of a distributor for distributing refrigerant to at least a portion of a tube bundle in the evaporator provides increased performance of the evaporator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application No. 61/020,533, entitled FALLING FILM EVAPORATORSYSTEMS, filed Jan. 11, 2008, which is hereby incorporated by reference.

BACKGROUND

The application relates generally to vapor compression systems inrefrigeration, air conditioning and chilled liquid systems. Theapplication relates more specifically to distribution systems andmethods in vapor compression systems.

Conventional chilled liquid systems used in heating, ventilation and airconditioning systems include an evaporator to affect a transfer ofthermal energy between the refrigerant of the system and another liquidto be cooled. One type of evaporator includes a shell with a pluralityof tubes forming a tube bundle(s) through which the liquid to be cooledis circulated. The refrigerant is brought into contact with the outer orexterior surfaces of the tube bundle inside the shell, resulting in atransfer of thermal energy between the liquid to be cooled and therefrigerant. For example, refrigerant can be deposited onto the exteriorsurfaces of the tube bundle by spraying or other similar techniques inwhat is commonly referred to as a “falling film” evaporator. In afurther example, the exterior surfaces of the tube bundle can be fullyor partially immersed in liquid refrigerant in what is commonly referredto as a “flooded” evaporator. In yet another example, a portion of thetube bundle can have refrigerant deposited on the exterior surfaces andanother portion of the tube bundle can be immersed in liquid refrigerantin what is commonly referred to as a “hybrid falling film” evaporator.

As a result of the thermal energy transfer with the liquid, therefrigerant is heated and converted to a vapor state, which is thenreturned to a compressor where the vapor is compressed, to begin anotherrefrigerant cycle. The cooled liquid can be circulated to a plurality ofheat exchangers located throughout a building. Warmer air from thebuilding is passed over the heat exchangers where the cooled liquid iswarmed, while cooling the air for the building. The liquid warmed by thebuilding air is returned to the evaporator to repeat the process.

SUMMARY

The present invention relates to a heat exchanger for use in a vaporcompression system having a shell, a tube bundle, a hood, and adistributor. The tube bundle has a plurality of tubes extendingsubstantially horizontally in the shell and the hood covers the tubebundle. The distributor mixes vapor and liquid entering the distributorto form a mixed fluid. The distributor is positioned to apply the mixedfluid to the tube bundle.

The present invention also relates to a heat exchanger for use in avapor compression system having a shell, a tube bundle, a hood, and adistributor. The tube bundle includes a plurality of tubes extendingsubstantially horizontally in the shell. The hood covers the tubebundle, and the distributor includes a first distribution devicepositioned to distribute vapor refrigerant. The distributor alsoincludes a second distribution device positioned to apply liquidrefrigerant to the tube bundle.

The present invention also relates to a heat exchanger for a vaporcompression system including a shell, a tube bundle, a hood, adistributor, and an inlet connection. The heat exchanger also includes arefrigerant line connecting the inlet connection and the distributor.The tube bundle includes a plurality of tubes extending substantiallyhorizontally in the shell. The hood covers the tube bundle and therefrigerant line is positioned to enable refrigerant in the refrigerantline to enter into a heat transfer relationship with refrigerant in theheat exchanger.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an exemplary embodiment for a heating, ventilation and airconditioning system.

FIG. 2 shows an isometric view of an exemplary vapor compression system.

FIGS. 3 and 4 schematically illustrate exemplary embodiments of thevapor compression system.

FIG. 5A shows an exploded, partial cutaway view of an exemplaryevaporator.

FIG. 5B shows a top isometric view of the evaporator of FIG. 5A.

FIG. 5C shows a cross section of the evaporator taken along line 5-5 ofFIG. 5B.

FIG. 6A shows a top isometric view of an exemplary evaporator.

FIGS. 6B and 6C show a cross section of the evaporator taken along line6-6 of FIG. 6A.

FIG. 7A shows a partial cross section of an evaporator with an exemplarydistributor.

FIG. 7B shows an enlarged partial bottom view of the distributor of FIG.7A.

FIG. 8A shows a partial cross section of an evaporator with anotherexemplary distributor.

FIG. 8B shows an enlarged partial cross section of the distributor ofFIG. 8A.

FIGS. 9 and 10 show elevation views of exemplary embodiments ofdistributors for an evaporator.

FIG. 11 shows a cross section of an exemplary baffled distributor for anevaporator.

FIG. 12 shows a cross section of an exemplary wire mesh distributor foran evaporator.

FIGS. 13 and 14 show cross sections of exemplary embodiments ofdistributors for an evaporator.

FIGS. 15, 16 and 17 show cross sections of exemplary embodiments ofdistributors for an evaporator.

FIG. 18 shows an exemplary distributor for an evaporator.

FIG. 19 shows a cross section of the distributor taken along line 19-19of FIG. 18.

FIG. 20 shows another exemplary distributor for an evaporator.

FIG. 21 shows an exemplary embodiment of a venturi inlet for adistributor.

FIGS. 22 and 23 show cross sections of evaporators with exemplarydistributors.

FIG. 24 shows a cross section of an evaporator with an exemplarydistributor.

FIG. 25 shows a cross section of an evaporator with an exemplarydistributor.

FIG. 26A shows a cross section of an exemplary heat exchanger.

FIG. 26B shows an exemplary vapor compression system with the heatexchanger of FIG. 26A.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 shows an exemplary environment for a heating, ventilation and airconditioning (HVAC) system 10 incorporating a chilled liquid system in abuilding 12 for a typical commercial setting. System 10 can include avapor compression system 14 that can supply a chilled liquid, which maybe used to cool building 12. System 10 can include a boiler 16 to supplyheated liquid that may be used to heat building 12, and an airdistribution system, which circulates air through building 12. The airdistribution system can also include an air return duct 18, an airsupply duct 20 and an air handler 22. Air handler 22 can include a heatexchanger that is connected to boiler 16 and vapor compression system 14by conduits 24. The heat exchanger in air handler 22 may receive eitherheated liquid from boiler 16 or chilled liquid from vapor compressionsystem 14, depending on the mode of operation of system 10. System 10 isshown with a separate air handler on each floor of building 12, but itis appreciated that the components may be shared between or amongfloors.

FIGS. 2 and 3 show an exemplary vapor compression system 14 that can beused in an HVAC system, such as HVAC system 10. Vapor compression system14 can circulate a refrigerant through a compressor 32 driven by a motor50, a condenser 34, expansion device(s) 36, and a liquid chiller orevaporator 38. Vapor compression system 14 can also include a controlpanel 40 that can include an analog to digital (A/D) converter 42, amicroprocessor 44, a non-volatile memory 46, and an interface board 48.Some examples of fluids that may be used as refrigerants in vaporcompression system 14 are hydrofluorocarbon (HFC) based refrigerants,for example, R-410A, R-407, R-134a, hydrofluoro olefin (HFO), “natural”refrigerants like ammonia (NH₃), R-717, carbon dioxide (CO₂), R-744, orhydrocarbon based refrigerants, water vapor or any other suitable typeof refrigerant. In an exemplary embodiment, vapor compression system 14may use one or more of each of VSDs 52, motors 50, compressors 32,condensers 34 and/or evaporators 38.

Motor 50 used with compressor 32 can be powered by a variable speeddrive (VSD) 52 or can be powered directly from an alternating current(AC) or direct current (DC) power source. VSD 52, if used, receives ACpower having a particular fixed line voltage and fixed line frequencyfrom the AC power source and provides power having a variable voltageand frequency to motor 50. Motor 50 can include any type of electricmotor that can be powered by a VSD or directly from an AC or DC powersource. For example, motor 50 can be a switched reluctance motor, aninduction motor, an electronically commutated permanent magnet motor orany other suitable motor type. In an alternate exemplary embodiment,other drive mechanisms such as steam or gas turbines or engines andassociated components can be used to drive compressor 32.

Compressor 32 compresses a refrigerant vapor and delivers the vapor tocondenser 34 through a discharge line. Compressor 32 can be acentrifugal compressor, screw compressor, reciprocating compressor,rotary compressor, swing link compressor, scroll compressor, turbinecompressor, or any other suitable compressor. The refrigerant vapordelivered by compressor 32 to condenser 34 transfers heat to a fluid,for example, water or air. The refrigerant vapor condenses to arefrigerant liquid in condenser 34 as a result of the heat transfer withthe fluid. The liquid refrigerant from condenser 34 flows throughexpansion device 36 to evaporator 38. In the exemplary embodiment shownin FIG. 3, condenser 34 is water cooled and includes a tube bundle 54connected to a cooling tower 56.

The liquid refrigerant delivered to evaporator 38 absorbs heat fromanother fluid, which may or may not be the same type of fluid used forcondenser 34, and undergoes a phase change to a refrigerant vapor. Inthe exemplary embodiment shown in FIG. 3, evaporator 38 includes a tubebundle having a supply line 60S and a return line 60R connected to acooling load 62. A process fluid, for example, water, ethylene glycol,calcium chloride brine, sodium chloride brine, or any other suitableliquid, enters evaporator 38 via return line 60R and exits evaporator 38via supply line 60S. Evaporator 38 chills the temperature of the processfluid in the tubes. The tube bundle in evaporator 38 can include aplurality of tubes and a plurality of tube bundles. The vaporrefrigerant exits evaporator 38 and returns to compressor 32 by asuction line to complete the cycle.

FIG. 4, which is similar to FIG. 3, shows the refrigerant circuit withan intermediate circuit 64 that may be incorporated between condenser 34and expansion device 36 to provide increased cooling capacity,efficiency and performance. Intermediate circuit 64 has an inlet line 68that can be either connected directly to or can be in fluidcommunication with condenser 34. As shown, inlet line 68 includes anexpansion device 66 positioned upstream of an intermediate vessel 70.Intermediate vessel 70 can be a flash tank, also referred to as a flashintercooler, in an exemplary embodiment. In an alternate exemplaryembodiment, intermediate vessel 70 can be configured as a heat exchangeror a “surface economizer”. In the flash intercooler arrangement, a firstexpansion device 66 operates to lower the pressure of the liquidreceived from condenser 34. During the expansion process in a flashintercooler, a portion of the liquid is evaporated. Intermediate vessel70 may be used to separate the evaporated vapor from the liquid receivedfrom the condenser. The evaporated liquid may be drawn by compressor 32to a port at a pressure intermediate between suction and discharge or atan intermediate stage of compression, through a line 74. The liquid thatis not evaporated is cooled by the expansion process, and collects atthe bottom of intermediate vessel 70, where the liquid is recovered toflow to the evaporator 38, through a line 72 comprising a secondexpansion device 36.

In the “surface intercooler” arrangement, the implementation is slightlydifferent, as known to those skilled in the art. Intermediate circuit 64can operate in a similar matter to that described above, except thatinstead of receiving the entire amount of refrigerant from condenser 34,as shown in FIG. 4, intermediate circuit 64 receives only a portion ofthe refrigerant from condenser 34 and the remaining refrigerant proceedsdirectly to expansion device 36.

FIGS. 5A through 5C show an exemplary embodiment of an evaporatorconfigured as a “hybrid falling film” evaporator. As shown in FIGS. 5Athrough 5C, an evaporator 138 includes a substantially cylindrical shell76 with a plurality of tubes forming a tube bundle 78 extendingsubstantially horizontally along the length of shell 76. At least onesupport 116 may be positioned inside shell 76 to support the pluralityof tubes in tube bundle 78. A suitable fluid, such as water, ethylene,ethylene glycol, or calcium chloride brine flows through the tubes oftube bundle 78. A distributor 80 positioned above tube bundle 78distributes, deposits or applies refrigerant 110 from a plurality ofpositions onto the tubes in tube bundle 78. In one exemplary embodiment,the refrigerant deposited by distributor 80 can be entirely liquidrefrigerant, although in another exemplary embodiment, the refrigerantdeposited by distributor 80 can include both liquid refrigerant andvapor refrigerant.

Liquid refrigerant that flows around the tubes of tube bundle 78 withoutchanging state collects in the lower portion of shell 76. The collectedliquid refrigerant can form a pool or reservoir of liquid refrigerant82. The deposition positions from distributor 80 can include anycombination of longitudinal or lateral positions with respect to tubebundle 78. In another exemplary embodiment, deposition positions fromdistributor 80 are not limited to ones that deposit onto the upper tubesof tube bundle 78. Distributor 80 may include a plurality of nozzlessupplied by a dispersion source of the refrigerant. In an exemplaryembodiment, the dispersion source is a tube connecting a source ofrefrigerant, such as condenser 34. Nozzles include spraying nozzles, butalso include machined openings that can guide or direct refrigerant ontothe surfaces of the tubes. The nozzles may apply refrigerant in apredetermined pattern, such as a jet pattern, so that the upper row oftubes of tube bundle 78 are covered. The tubes of tube bundle 78 can bearranged to promote the flow of refrigerant in the form of a film aroundthe tube surfaces, the liquid refrigerant coalescing to form droplets orin some instances, a curtain or sheet of liquid refrigerant at thebottom of the tube surfaces. The resulting sheeting promotes wetting ofthe tube surfaces which enhances the heat transfer efficiency betweenthe fluid flowing inside the tubes of tube bundle 78 and the refrigerantflowing around the surfaces of the tubes of tube bundle 78.

In the pool of liquid refrigerant 82, a tube bundle 140 can be immersedor at least partially immersed, to provide additional thermal energytransfer between the refrigerant and the process fluid to evaporate thepool of liquid refrigerant 82. In an exemplary embodiment, tube bundle78 can be positioned at least partially above (that is, at leastpartially overlying) tube bundle 140. In one exemplary embodiment,evaporator 138 incorporates a two pass system, in which the processfluid that is to be cooled first flows inside the tubes of tube bundle140 and then is directed to flow inside the tubes of tube bundle 78 inthe opposite direction to the flow in tube bundle 140. In the secondpass of the two pass system, the temperature of the fluid flowing intube bundle 78 is reduced, thus requiring a lesser amount of heattransfer with the refrigerant flowing over the surfaces of tube bundle78 to obtain a desired temperature of the process fluid.

It is to be understood that although a two pass system is described inwhich the first pass is associated with tube bundle 140 and the secondpass is associated with tube bundle 78, other arrangements arecontemplated. For example, evaporator 138 can incorporate a one passsystem where the process fluid flows through both tube bundle 140 andtube bundle 78 in the same direction. Alternatively, evaporator 138 canincorporate a three pass system in which two passes are associated withtube bundle 140 and the remaining pass associated with tube bundle 78,or in which one pass is associated with tube bundle 140 and theremaining two passes are associated with tube bundle 78. Further,evaporator 138 can incorporate an alternate two pass system in which onepass is associated with both tube bundle 78 and tube bundle 140, and thesecond pass is associated with both tube bundle 78 and tube bundle 140.In one exemplary embodiment, tube bundle 78 is positioned at leastpartially above tube bundle 140, with a gap separating tube bundle 78from tube bundle 140. In a further exemplary embodiment, hood 86overlies tube bundle 78, with hood 86 extending toward and terminatingnear the gap. In summary, any number of passes in which each pass can beassociated with one or both of tube bundle 78 and tube bundle 140 iscontemplated.

An enclosure or hood 86 is positioned over tube bundle 78 tosubstantially prevent cross flow, that is, a lateral flow of vaporrefrigerant or liquid and vapor refrigerant 106 between the tubes oftube bundle 78. Hood 86 is positioned over and laterally borders tubesof tube bundle 78. Hood 86 includes an upper end 88 positioned near theupper portion of shell 76. Distributor 80 can be positioned between hood86 and tube bundle 78. In yet a further exemplary embodiment,distributor 80 may be positioned near, but exterior of, hood 86, so thatdistributor 80 is not positioned between hood 86 and tube bundle 78.However, even though distributor 80 is not positioned between hood 86and tube bundle 78, the nozzles of distributor 80 are still configuredto direct or apply refrigerant onto surfaces of the tubes. Upper end 88of hood 86 is configured to substantially prevent the flow of appliedrefrigerant 110 and partially evaporated refrigerant, that is, liquidand/or vapor refrigerant 106 from flowing directly to outlet 104.Instead, applied refrigerant 110 and refrigerant 106 are constrained byhood 86, and, more specifically, are forced to travel downward betweenwalls 92 before the refrigerant can exit through an open end 94 in thehood 86. Flow of vapor refrigerant 96 around hood 86 also includesevaporated refrigerant flowing away from the pool of liquid refrigerant82.

It is to be understood that at least the above-identified, relativeterms are non-limiting as to other exemplary embodiments in thedisclosure. For example, hood 86 may be rotated with respect to theother evaporator components previously discussed, that is, hood 86,including walls 92, is not limited to a vertical orientation. Uponsufficient rotation of hood 86 about an axis substantially parallel tothe tubes of tube bundle 78, hood 86 may no longer be considered“positioned over” nor to “laterally border” tubes of tube bundle 78.Similarly, “upper” end 88 of hood 86 may no longer be near “an upperportion” of shell 76, and other exemplary embodiments are not limited tosuch an arrangement between the hood and the shell. In an exemplaryembodiment, hood 86 terminates after covering tube bundle 78, althoughin another exemplary embodiment, hood 86 further extends after coveringtube bundle 78.

After hood 86 forces refrigerant 106 downward between walls 92 andthrough open end 94, the vapor refrigerant undergoes an abrupt change indirection before traveling in the space between shell 76 and walls 92from the lower portion of shell 76 to the upper portion of shell 76.Combined with the effect of gravity, the abrupt directional change inflow results in a proportion of any entrained droplets of refrigerantcolliding with either liquid refrigerant 82 or shell 76, therebyremoving those droplets from the flow of vapor refrigerant 96. Also,refrigerant mist traveling along the length of hood 86 between walls 92is coalesced into larger drops that are more easily separated bygravity, or maintained sufficiently near or in contact with tube bundle78, to permit evaporation of the refrigerant mist by heat transfer withthe tube bundle. As a result of the increased drop size, the efficiencyof liquid separation by gravity is improved, permitting an increasedupward velocity of vapor refrigerant 96 flowing through the evaporatorin the space between walls 92 and shell 76. Vapor refrigerant 96,whether flowing from open end 94 or from the pool of liquid refrigerant82, flows over a pair of extensions 98 protruding from walls 92 nearupper end 88 and into a channel 100. Vapor refrigerant 96 enters intochannel 100 through slots 102, which is the space between the ends ofextensions 98 and shell 76, before exiting evaporator 138 at an outlet104. In another exemplary embodiment, vapor refrigerant 96 can enterinto channel 100 through openings or apertures formed in extensions 98,instead of slots 102. In yet another exemplary embodiment, slots 102 canbe formed by the space between hood 86 and shell 76, that is, hood 86does not include extensions 98.

Stated another way, once refrigerant 106 exits from hood 86, vaporrefrigerant 96 then flows from the lower portion of shell 76 to theupper portion of shell 76 along the prescribed passageway. In anexemplary embodiment, the passageways can be substantially symmetricbetween the surfaces of hood 86 and shell 76 prior to reaching outlet104. In an exemplary embodiment, baffles, such as extensions 98 areprovided near the evaporator outlet to prevent a direct path of vaporrefrigerant 96 to the compressor inlet.

In one exemplary embodiment, hood 86 includes opposed substantiallyparallel walls 92. In another exemplary embodiment, walls 92 can extendsubstantially vertically and terminate at open end 94, that is locatedsubstantially opposite upper end 88. Upper end 88 and walls 92 areclosely positioned near the tubes of tube bundle 78, with walls 92extending toward the lower portion of shell 76 so as to substantiallylaterally border the tubes of tube bundle 78. In an exemplaryembodiment, walls 92 may be spaced between about 0.02 inch (0.5 mm) andabout 0.8 inch (20 mm) from the tubes in tube bundle 78. In a furtherexemplary embodiment, walls 92 may be spaced between about 0.1 inch (3mm) and about 0.2 inch (5 mm) from the tubes in tube bundle 78. However,spacing between upper end 88 and the tubes of tube bundle 78 may besignificantly greater than 0.2 inch (5 mm), in order to providesufficient spacing to position distributor 80 between the tubes and theupper end of the hood. In an exemplary embodiment in which walls 92 ofhood 86 are substantially parallel and shell 76 is cylindrical, walls 92may also be symmetric about a central vertical plane of symmetry of theshell bisecting the space separating walls 92. In other exemplaryembodiments, walls 92 need not extend vertically past the lower tubes oftube bundle 78, nor do walls 92 need to be planar, as walls 92 may becurved or have other non-planar shapes. Regardless of the specificconstruction, hood 86 is configured to channel refrigerant 106 withinthe confines of walls 92 through open end 94 of hood 86.

FIGS. 6A through 6C show an exemplary embodiment of an evaporatorconfigured as a “falling film” evaporator 128. As shown in FIGS. 6Athrough 6C, evaporator 128 is similar to evaporator 138 shown in FIGS.5A through 5C, except that evaporator 128 does not include tube bundle140 in the pool of refrigerant 82 that collects in the lower portion ofthe shell. In an exemplary embodiment, hood 86 terminates after coveringtube bundle 78, although in another exemplary embodiment, hood 86further extends toward pool of refrigerant 82 after covering tube bundle78. In yet a further exemplary embodiment, hood 86 terminates so thatthe hood does not totally cover the tube bundle, that is, substantiallycovers the tube bundle.

As shown in FIGS. 6B and 6C, a pump 84 can be used to recirculate thepool of liquid refrigerant 82 from the lower portion of the shell 76 vialine 114 to distributor 80. As further shown in FIG. 6B, line 114 caninclude a regulating device 112 that can be in fluid communication witha condenser (not shown). In another exemplary embodiment, an ejector(not shown) can be employed to draw liquid refrigerant 82 from the lowerportion of shell 76 using the pressurized refrigerant from condenser 34,which operates by virtue of the Bernoulli effect. The ejector combinesthe functions of a regulating device 112 and a pump 84.

In an exemplary embodiment, one arrangement of tubes or tube bundles maybe defined by a plurality of uniformly spaced tubes that are alignedvertically and horizontally, forming an outline that can besubstantially rectangular. However, a stacking arrangement of tubebundles can be used where the tubes are neither vertically orhorizontally aligned, as well as arrangements that are not uniformlyspaced.

In another exemplary embodiment, different tube bundle constructions arecontemplated. For example, finned tubes (not shown) can be used in atube bundle, such as along the uppermost horizontal row or uppermostportion of the tube bundle. Besides the possibility of using finnedtubes, tubes developed for more efficient operation for pool boilingapplications, such as in “flooded” evaporators, may also be employed.Additionally, or in combination with the finned tubes, porous coatingscan also be applied to the outer surface of the tubes of the tubebundles.

In a further exemplary embodiment, the cross-sectional profile of theevaporator shell may be non-circular.

In an exemplary embodiment, a portion of the hood may partially extendinto the shell outlet.

In addition, it is possible to incorporate the expansion functionalityof the expansion devices of system 14 into distributor 80. In oneexemplary embodiment, two expansion devices may be employed. Oneexpansion device is exhibited in the spraying nozzles of distributor 80.The other expansion device, for example, expansion device 36, canprovide a preliminary partial expansion of refrigerant, before thatprovided by the spraying nozzles positioned inside the evaporator. In anexemplary embodiment, the other expansion device, that is, thenon-spraying nozzle expansion device, can be controlled by the level ofliquid refrigerant 82 in the evaporator to account for variations inoperating conditions, such as evaporating and condensing pressures, aswell as partial cooling loads. In an alternative exemplary embodiment,expansion device can be controlled by the level of liquid refrigerant inthe condenser, or in a further exemplary embodiment, a “flasheconomizer” vessel. In one exemplary embodiment, the majority of theexpansion can occur in the nozzles, providing a greater pressuredifference, while simultaneously permitting the nozzles to be of reducedsize, therefore reducing the size and cost of the nozzles.

As shown in FIG. 7A, distributor 80 includes at least one aperture 142formed in an upper section 144 of distributor 80 to permit vaporrefrigerant to be separated from liquid refrigerant before therefrigerant is distributed over tube bundle 78. Refrigerant may enterdistributor 80 as a two-state refrigerant from a condenser or othersource (not shown). The pressure of the refrigerant flow from thecondenser or other source provides the necessary force for therefrigerant to flow through distributor 80. A pump may be used toprovide additional force for refrigerant flow through distributor 80.The inlet to the distributor (not shown) may be located or formed in theupper section 144 of distributor 80, or at an end of the distributor(not shown). Apertures 142 permit vapor refrigerant to exit distributor80 without being directly distributed over tube bundle 78. FIG. 7A showsapertures 142 as being located at the uppermost portion of upper section144, however apertures 142 may be located on any suitable portion ofupper section 144. In an exemplary embodiment, apertures 142 may haveany suitable shape for distributing vapor refrigerant. Liquidrefrigerant is distributed on tube bundle 78 through openings 146 formedin the lower section 148 of distributor 80. Openings 146 are shown inFIG. 7B as paired or double openings, however openings 146 may be singleopenings or three or more openings. In an exemplary embodiment, openings146 may have any suitable shape for distributing liquid refrigerant ontotube bundle 78.

FIGS. 8A and 8B show another embodiment of distributor 80 used in anevaporator. Distributor 240 can be positioned within hood 86, and has aninner distributor 150 and an outer distributor 152. Distributors 150 and152 may also be referred to as compartments or chambers. At least oneaperture 154 may be formed in an upper portion 156 of inner distributor150 to permit vapor refrigerant to flow from inner distributor 150 intoouter distributor 152. While FIG. 8A shows apertures 154 having a tubeinserted in upper portion 156, aperture 154 may be integrally formedwithin upper portion 156. Openings 146 may be formed or disposed in thebottom segment 130 of inner distributor 150 to allow liquid refrigerantto flow into outer distributor 152.

Outer distributor 152 can have apertures 142 formed in lateral portionsor walls 158 of outer distributor 152 to permit vapor refrigerant toflow from outer distributor 152 into the space under hood 86. While FIG.8A shows apertures 142 having a tube inserted in lateral portions 158,apertures 142 may be integrally formed in lateral portions 158 of outerdistributor 152. Liquid refrigerant may collect in a bottom portion 160of outer distributor 152 and flow through distribution devices 162positioned in bottom portion 160 of outer distributor 152. Distributiondevices 162 permit the distribution of liquid refrigerant from outerdistributor 152 onto tube bundle 78 for heat transfer between therefrigerant and the process fluid in tube bundle 78. Distributiondevices 162 may be nozzles, holes, openings, valves or any othersuitable device. In another exemplary embodiment, distribution devices162 may be integrally formed with outer distributor 152. FIG. 8B showsan embodiment of outer distributor 152 with distribution devices 162positioned with little or minimal space between adjacent neighboringflow distribution devices 162. In an exemplary embodiment, outerdistributor 152 may have a corrugated bottom to reduce the amount ofrefrigerant required to maintain a flow of liquid refrigerant todistribution devices 162.

Referring now to FIGS. 9 and 10, exemplary embodiments for respectivedistributors 242 and 244 are shown. Distributors 242 and 244 may includemultiple inlet lines 68, also referred to as flow paths or flowportions, to receive refrigerant. Each inlet line 68 can be in fluidcommunication with each other, and each inlet line 68 can receive bothliquid refrigerant and vapor refrigerant. Inlet lines 68 connect to line164 that provides refrigerant to distribution devices 162. Distributiondevices 162 distribute refrigerant over tube bundle 78. Distributors 242and 244 may include a separator (not shown) to separate vaporrefrigerant and liquid refrigerant before refrigerant is provided toinlet lines 68 to be distributed onto tube bundle 78. The vaporrefrigerant from the separator may be provided to a compressor.Distributors 242 and 244 may also include various flow controlcomponents to regulate the flow of refrigerant in inlet lines 68. Theflow control components may include, but are not limited to, oscillatingflow, pulse widths, or a pump to modulate the flow of refrigerant.Distribution devices 162 may be nozzles, valves, openings or any othersuitable distribution device. In an exemplary embodiment, distributiondevices 162 may be oscillating nozzles used to oscillate the refrigerantprovided onto tube bundle 78. In the exemplary embodiment shown in FIG.10, line 164 is connected to second line 224 by a connection line 226 toprovide refrigerant onto additional tubes of tube bundle 78. Line 164can be positioned above second line 224.

FIGS. 11 and 12 show embodiments of distributors that can controlrefrigerant flow 236 and the supply of refrigerant to distributiondevices 162. In a distributor 246 shown in FIG. 11, a series of baffles166 can be positioned in predetermined locations in distributor 246.Baffles 166 are shown alternately protruding inwardly from oppositesides of distributor 246. The alternate placement of baffles 166provides a flow pattern for the refrigerant that provides more uniformrefrigerant supply to distribution devices 162. In distributor 248 shownin FIG. 12, a wire mesh 168 may be positioned in distributor 248 tocontrol refrigerant flow 236 through distributor 248 and the supply ofrefrigerant to distribution devices 162. Both baffles 166 and wire mesh168 provide for refrigerant flow 236 that is a mixture of liquidrefrigerant and vapor refrigerant before refrigerant is distributed totube bundle 78 by distribution devices 162.

FIGS. 13 and 14 show a distributor 250 having protrusions 194 forregulating refrigerant flow 236 through distributor 250. As shown inFIG. 13, protrusions 194 can be positioned along the bottom surface 196near distribution devices 162 to interrupt direct refrigerant flow todistribution devices 162. As shown in FIG. 14, protrusions 194 can bepositioned along the top surface 198 opposite distribution devices 162.Protrusions 194 provide for refrigerant flow 236 that is a mixture ofliquid refrigerant and vapor refrigerant. In another exemplaryembodiment, protrusions 194 may be positioned on both top surface 198and bottom surface 196 in distributor 250 to control refrigerant flow236.

FIGS. 15 and 16 show enclosures or housings 170 for a distributor.Enclosures 170 can have a predetermined shape, such as, a rectangular,diamond, and/or square shape for improving refrigerant flow to tubebundle 78. Any suitable shape may be used for enclosures 170, so long asrefrigerant flow can be maintained through enclosure 170. Inlets (notshown) may be located at an upper portion of enclosure 170 or at theends of enclosure 170. Distribution devices 162, such as holes oropenings, can be formed or located on a bottom portion of enclosure 170to allow refrigerant 110 to flow onto tube bundles 78. Other exemplaryembodiments of enclosures 170 may include openings (not shown) in theupper portion of enclosure 170 to allow for the flow of vaporrefrigerant from enclosure 170. FIG. 17 shows an embodiment ofdistributor 80 for distributing refrigerant onto tube bundles 78.Distribution devices 162 are positioned in predetermined locations ondistributor 80. Distributor 80 may include more or less than the threeflow distribution devices shown in FIG. 17. In an exemplary embodiment,distribution devices 162 may be formed by a cutting tool, such as acutting tool with a rotating blade, or may be formed by other methods,such as a press. In a further exemplary embodiment, distribution devices162 may be formed in enclosure 170 prior to the enclosure being formedinto a final shape.

FIGS. 18 and 19 show an embodiment for a distributor 252 connected to aseparator 176 for separating liquid refrigerant from vapor refrigerantbefore the refrigerant enters distributor 252. Separator 176 receivestwo-phase refrigerant and separates the refrigerant into vaporrefrigerant and liquid refrigerant. A vapor line 178 exits from an upperportion of separator 176 and provides vapor refrigerant to a vaporrefrigerant line 188 in distributor 252. Vapor refrigerant line 188distributes vapor refrigerant onto tube bundle 78 in distributor 252. Aliquid line 182 exits from a lower portion of separator 176 and providesliquid refrigerant to a liquid refrigerant line 186 in distributor 252.Liquid refrigerant line 186 distributes liquid refrigerant onto tubebundles 78. Liquid refrigerant is distributed above the vaporrefrigerant in distributor 252. Vapor refrigerant and liquid refrigerantare distributed concurrently over tube bundle 78 to improve the heattransfer, or cooling, of tube bundle 78. The vapor refrigerant reducesthe film thickness of liquid refrigerant on tube bundle 78 and providesa more uniform distribution of refrigerant to tube bundle 78, resultingin more efficient heat transfer with tube bundle 78. Distributiondevices 162 are connected to liquid refrigerant line 186 and vaporrefrigerant line 188 and used to distribute both the liquid refrigerantand vapor refrigerant onto tube bundle 78. Distribution devices 162 maybe nozzles, openings or any other suitable distribution device, and maybe positioned in any suitable position.

Referring now to FIG. 20, a multiple branch distributor 190 may be usedto distribute refrigerant over tube bundles (not shown). Inlet line 68receives refrigerant, which then flows through distribution lines 192 todistribution devices 162. Distribution lines 192 may be positionedlaterally in relation to each other to provide refrigerant distributionto a greater surface area of the tube bundle. Applied refrigerant 110 isdistributed onto the tube bundle by distribution device 162.

FIG. 21 shows an exemplary embodiment of an inlet 254 that may be usedwith a distributor. Inlet 254 can operate to mix liquid and vaporrefrigerant that is entering the distributor with a tapered opening 200,such as a venturi or multiple venturi to control the flow ofrefrigerant. Refrigerant enters inlet 254 through a wider opening at afirst flow rate. Tapered opening 200 of inlet 254 then narrows thepassageway for the refrigerant from the opening in inlet 254. Thenarrowed opening or passageway results in an increase in the flow rateof the refrigerant to a second flow rate. The second flow rate permitsvapor and liquid refrigerant to mix, resulting in a mixed refrigerant ofboth liquid refrigerant and vapor refrigerant. The mixed refrigerantthen exits inlet 254 into the distributor through a wider opening at athird and slower flow rate than the second flow rate.

FIGS. 22 and 23 show distributors in evaporators 128 for distributingapplied refrigerant 110 onto tube bundles 78. As shown in FIG. 22,refrigerant enters inlet line 68 through the top of shell 76 and flowsthrough a tube 204 before passing through an expansion valve 202. Tube204 is positioned in the vapor section of evaporator 128. Refrigeranttravelling through tube 204 is cooled so that at least a portion ofvapor refrigerant in tube 204 can condense to liquid refrigerant and bedistributed by tube 206 to distributors 80. In addition, at least aportion of liquid refrigerant that may be entrained with vaporrefrigerant in the vapor section of evaporator 128 can be evaporated asa result of the heat transfer with the refrigerant in tube 204. As shownin FIG. 23, inlet line 68 may enter into pool of liquid refrigerant 82located at the bottom of evaporator 128. The liquid refrigerant canenter into a heat transfer relationship with the refrigerant in tube204, condensing at least a portion of vapor refrigerant in tube 204before entering expansion valve 202 and tube 206. In addition, liquidrefrigerant in pool of liquid refrigerant 82 may be evaporated as aresult of the heat transfer with the refrigerant in tube 204. In anotherexemplary embodiment, tube 204 may also pass through both the pool ofliquid refrigerant 82 and the vapor section of evaporator 128.

FIG. 24 shows an embodiment of a distributor with a heat exchanger 210in outlet 104. Heat exchanger 210 may be positioned between evaporator138 and a compressor (not shown). Refrigerant from the condenser canflow through heat exchanger 210 and an expansion device before reachinginlet line 68. A heat exchange relationship occurs between vaporrefrigerant 96 leaving evaporator 138 and the refrigerant in heatexchanger 210. Refrigerant in heat exchanger 210 is cooled, and at leasta portion of vapor refrigerant in heat exchanger 210 can be condensed.Vapor refrigerant 96 is heated by heat exchanger 210 and at least aportion of liquid refrigerant that may be entrained with vaporrefrigerant 96 is evaporated.

In another embodiment shown in FIG. 25, heat exchangers 216 arepositioned between hood 86 and shell 76 to remove at least a portion ofentrained liquid that may be present in vapor refrigerant. Refrigerantfrom the condenser can flow through heat exchangers 216 before reachingexpansion device 260. Refrigerant in heat exchangers 216 are cooled, andat least a portion of vapor refrigerant in heat exchangers 216 can becondensed. Refrigerant then flows through expansion device 260 beforebeing distributed over tube bundle 78 and collecting at the bottom 262of evaporator 138. Vapor refrigerant 96 flows over heat exchanger 216before exiting through outlet 104 into the compressor and at least aportion of liquid refrigerant that may be entrained with vaporrefrigerant 96 is evaporated.

As shown in FIG. 26A, a heat exchanger 220 can exhibit a tube-in-tube,or pipe-in-pipe configuration. A line carrying refrigerant R2 may bepositioned within a line carrying refrigerant R1. In another exemplaryembodiment, the line carrying refrigerant R1 may be positioned withinthe line carrying refrigerant R2. The pipe-in-pipe configurationprovides for heat exchange between refrigerant R1 and refrigerant R2,where the temperature of refrigerant R1 is further lowered beforeentering evaporator 128. By lowering the temperature of refrigerant R1entering evaporator 128, the amount of vapor refrigerant in refrigerantR1 is reduced before entering evaporator 128, which can result in moreefficient heat transfer in evaporator 128 since most, if not all, of therefrigerant entering evaporator 128 can be evaporated.

FIG. 26B shows an exemplary embodiment of vapor compression system 14.Heat exchanger 220 can reduce the amount of vapor refrigerant providedto evaporator 128. Refrigerant exits condenser 34 and flows througheither expansion device 234 before entering heat exchanger 220 ordirectly into heat exchanger 220. Expansion device 234 reduces thepressure of the refrigerant leaving condenser 34 and entering heatexchanger 220. From expansion device 234, the refrigerant enters heatexchanger 220 and is heated by the other refrigerant that did not flowthrough expansion device 234. Refrigerant R1 in heat exchanger 220 (seeFIG. 26A) is cooled by transferring heat with refrigerant R2 in heatexchanger 220 (see FIG. 26A). From heat exchanger 220, refrigerant R1flows to expansion device 202 and evaporator 128, and refrigerant R2flows through line 218 to compressor 32.

While only certain features and embodiments of the invention have beenshown and described, many modifications and changes may occur to thoseskilled in the art (for example, variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters (for example, temperatures, pressures, etc.), mountingarrangements, use of materials, colors, orientations, etc.) withoutmaterially departing from the novel teachings and advantages of thesubject matter recited in the claims. The order or sequence of anyprocess or method steps may be varied or re-sequenced according toalternative embodiments. It is, therefore, to be understood that theappended claims are intended to cover all such modifications and changesas fall within the true spirit of the invention. Furthermore, in aneffort to provide a concise description of the exemplary embodiments,all features of an actual implementation may not have been described(that is, those unrelated to the presently contemplated best mode ofcarrying out the invention, or those unrelated to enabling the claimedinvention). It should be appreciated that in the development of any suchactual implementation, as in any engineering or design project, numerousimplementation specific decisions may be made. Such a development effortmight be complex and time consuming, but would nevertheless be a routineundertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure, without undueexperimentation.

1. A heat exchanger for use in a vapor compression system comprising: ashell; a tube bundle; a hood; a distributor; and the tube bundlecomprising a plurality of tubes extending substantially horizontally inthe shell; the hood covers the tube bundle; and the distributor isconfigured to mix vapor and liquid entering the distributor to form amixed fluid, the distributor being positioned and configured to applythe mixed fluid to the tube bundle.
 2. The heat exchanger of claim 1,wherein the distributor comprises a plurality of baffles configured andpositioned to provide a flow path in the distributor to mix liquid andvapor.
 3. The heat exchanger of claim 2, wherein the plurality ofbaffles are alternately positioned on opposed surfaces of thedistributor.
 4. The heat exchanger of claim 1, wherein the distributorcomprises a wire mesh configured and positioned to provide a flow pathin the distributor to mix liquid and vapor.
 5. The heat exchanger ofclaim 1, wherein the distributor comprises a plurality of protrusionsconfigured and positioned to provide a flow path in the distributor tomix liquid and vapor.
 6. The heat exchanger of claim 5, wherein thedistributor comprises a plurality of openings positioned and configuredto apply the mixed fluid to the tube bundle and the plurality ofprotrusions are positioned near the plurality of openings.
 7. The heatexchanger of claim 5, wherein the distributor comprises a plurality ofopenings positioned and configured to apply the mixed fluid to the tubebundle and the plurality of protrusions are positioned opposite theplurality of openings.
 8. A heat exchanger for use in a vaporcompression system comprising: a shell; a tube bundle; a hood; adistributor; the tube bundle comprises a plurality of tubes extendingsubstantially horizontally in the shell; the hood covers the tubebundle; and the distributor comprising a first distribution deviceconfigured and positioned to distribute vapor refrigerant and a seconddistribution device configured and positioned to apply liquidrefrigerant to the tube bundle.
 9. The heat exchanger of claim 8,wherein the distributor is configured to separate liquid refrigerantfrom vapor refrigerant in a flow of refrigerant entering thedistributor.
 10. The heat exchanger of claim 9, wherein the firstdistribution device is integral with the second distribution device. 11.The heat exchanger of claim 10, wherein the first distribution devicecomprises at least one opening and the second distribution devicecomprises at least one opening.
 12. The heat exchanger of claim 9,wherein the distributor comprises a first chamber, the firstdistribution device comprises at least one opening in the first chamberand the second distribution device comprises at least one opening in thefirst chamber.
 13. The heat exchanger of claim 12, wherein thedistributor comprises a second chamber positioned in the first chamber,the second chamber being configured and positioned to receive the flowof refrigerant entering the distributor, and the first distributiondevice comprises a least one opening in the second chamber and thesecond distribution device comprises a least one opening in the secondchamber.
 14. The heat exchanger of claim 8, wherein the distributor isconfigured and positioned to receive liquid refrigerant by a liquidrefrigerant line and vapor refrigerant by a vapor refrigerant line. 15.The heat exchanger of claim 14, wherein the second distribution deviceis positioned above the first distribution device, the seconddistribution device being connected to the liquid refrigerant line andthe first distribution device being connected to the vapor refrigerantline.
 16. The heat exchanger of claim 15, wherein the first distributiondevice is configured to distribute vapor refrigerant transverse to theliquid refrigerant applied by the second distribution device.
 17. A heatexchanger for a vapor compression system comprising: a shell; a tubebundle; a hood; a distributor; an inlet connection; a refrigerant lineconnecting the inlet connection and the distributor; the tube bundlecomprising a plurality of tubes extending substantially horizontally inthe shell; the hood covers the tube bundle; and the refrigerant line isconfigured and positioned to enable refrigerant in the refrigerant lineto enter into a heat transfer relationship with refrigerant in the heatexchanger.
 18. The heat exchanger of claim 17, wherein the refrigerantline is configured and positioned in the shell to be surrounded by vaporrefrigerant in the shell.
 19. The heat exchanger of claim 17, whereinthe refrigerant line is configured and positioned in the shell to besurrounded by liquid refrigerant in the shell.
 20. The heat exchanger ofclaim 17, further comprises an outlet connection and at least a portionof the refrigerant line is positioned in the outlet connection.
 21. Theheat exchanger of claim 18, wherein the refrigerant line comprises asecond plurality of tubes, the second plurality of tubes beingpositioned near the hood.